[commit: testsuite] wip/T8541: Test case for undersaturated newtype in Coercions (90554a8)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/testsuite

On branch  : wip/T8541
Link       : http://ghc.haskell.org/trac/ghc/changeset/90554a88bee5b492b4d4625ef30b23b9a7915347/testsuite

>---------------------------------------------------------------

commit 90554a88bee5b492b4d4625ef30b23b9a7915347
Author: Joachim Breitner <mail at joachim-breitner.de>
Date:   Tue Nov 19 12:01:27 2013 +0000

    Test case for undersaturated newtype in Coercions
    
    This is related to #8541.


>---------------------------------------------------------------

90554a88bee5b492b4d4625ef30b23b9a7915347
 tests/typecheck/should_fail/TcCoercibleFail3.hs     |   14 ++++++++++++++
 tests/typecheck/should_fail/TcCoercibleFail3.stderr |    7 +++++++
 tests/typecheck/should_fail/all.T                   |    1 +
 3 files changed, 22 insertions(+)

diff --git a/tests/typecheck/should_fail/TcCoercibleFail3.hs b/tests/typecheck/should_fail/TcCoercibleFail3.hs
new file mode 100644
index 0000000..4caf1c2
--- /dev/null
+++ b/tests/typecheck/should_fail/TcCoercibleFail3.hs
@@ -0,0 +1,14 @@
+{-# LANGUAGE RoleAnnotations, RankNTypes, ScopedTypeVariables #-}
+
+import GHC.Prim (coerce, Coercible)
+
+newtype List a = List [a]
+data T f = T (f Int)
+
+newtype NT1 a = NT1 (a -> Int)
+newtype NT2 a = NT2 (a -> Int)
+
+foo :: T NT1 -> T NT2
+foo = coerce
+
+main = return ()
diff --git a/tests/typecheck/should_fail/TcCoercibleFail3.stderr b/tests/typecheck/should_fail/TcCoercibleFail3.stderr
new file mode 100644
index 0000000..d3d71e1
--- /dev/null
+++ b/tests/typecheck/should_fail/TcCoercibleFail3.stderr
@@ -0,0 +1,7 @@
+
+TcCoercibleFail3.hs:12:7:
+    No instance for (Coercible NT1 NT2)
+      because ‛NT1’ and ‛NT2’ are different types.
+      arising from a use of ‛coerce’
+    In the expression: coerce
+    In an equation for ‛foo’: foo = coerce
diff --git a/tests/typecheck/should_fail/all.T b/tests/typecheck/should_fail/all.T
index f14bb5f..749ea32 100644
--- a/tests/typecheck/should_fail/all.T
+++ b/tests/typecheck/should_fail/all.T
@@ -319,6 +319,7 @@ test('T8262', normal, compile_fail, [''])
 test('TcCoercibleFail', when(compiler_lt('ghc', '7.7'), skip), compile_fail, [''])
 test('TcCoercibleFailSafe', when(compiler_lt('ghc', '7.7'), skip), compile_fail, [''])
 test('TcCoercibleFail2', when(compiler_lt('ghc', '7.7'), skip), compile_fail, [''])
+test('TcCoercibleFail3', when(compiler_lt('ghc', '7.7'), skip), compile_fail, [''])
 test('T8306', normal, compile_fail, [''])
 test('T8392a', normal, compile_fail, [''])
 test('T8428', normal, compile_fail, [''])